JPH09255495A - Silicon carbide film and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a silicon carbide film essentially free from defects in the film and having excellent crystallinity and surface homology to facilitate the control of the electrical properties, to obtain a substrate having the silicon carbide film and to provide a process for producing the film and the substrate. SOLUTION: This silicon carbide film has a surface roughness of <=10nm, preferably 0.5-3nm in terms of the center line average height (Ra) of the surface. It has a surface hillock density of <=200/cm<2> , preferably 0-100/cm<2> . The substrate has a silicon carbide film having the above properties. This process for the production of the silicon carbide film comprises the deposition of the silicon carbide film on a substrate having defects such as shape defect or crystal lattice defect.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a silicon carbide film having an excellent surface morphology, a substrate having a silicon carbide film having an excellent surface morphology, and a manufacturing method thereof. In particular, the present invention is a silicon carbide film excellent in surface morphology, and excellent in crystallinity and electrical characteristics by depositing silicon carbide on a substrate on which a defect serving as a gettering source is formed in advance, and its production. It provides a method. Silicon carbide film, which has excellent surface morphology and excellent crystallinity and electrical characteristics, is used for electronic devices such as semiconductor elements for high power used for power control and high frequency devices for communication, pressure sensors,
It is useful for various sensors such as acceleration sensor, optical sensor and temperature sensor.

[0002]

2. Description of the Related Art Silicon carbide is a semiconductor material having a wide band gap, excellent chemical stability and environmental resistance. Therefore, silicon carbide is expected as a material that can be used under high voltage, high temperature, or irradiation with radiation, which has been difficult to apply to conventional semiconductors centering on silicon.

Known methods of producing silicon carbide include a sublimation method, a liquid phase growth method and a vapor phase growth method. The sublimation method consists of a silicon carbide single crystal in which a gas obtained by sublimating silicon carbide as a raw material in a crucible at a temperature of 2000 to 2500 ° C. is placed above the raw material and set at a temperature 50 to 200 ° C. lower than that of the raw material. This is a method of depositing on a seed crystal to grow a silicon carbide single crystal [see, for example, Japanese Patent Publication No. 7-88274 and Japanese Patent Publication No. 7-91153].

In the liquid phase epitaxy method, a crucible containing carbon as a constituent element is used, and silicon is melted in the crucible at a temperature of 1650 to 1800 ° C. to form carbon and silicon which are constituent elements of the crucible in a silicon melt. Is a method of melting the silicon carbide generated by the reaction of (1) and growing single crystal silicon carbide on the seed crystal brought into contact with the surface of the melt (see, for example, JP-A-7-172998). The vapor phase growth method is a method in which a silicon source gas and a carbon source gas are supplied onto a substrate to deposit silicon carbide on the substrate surface [for example, JA Powell et al., Journal of Electrochemical. Society (J, Electrochem. Soc.) 13
4, (1987) 1558]. Further, by supplying these gases alternately into the reaction furnace, a highly uniform single crystal silicon carbide can be produced [see, for example, JP-A-7-118854].

[0005]

In the conventional method for depositing a silicon carbide single crystal by vapor phase epitaxy, particularly when depositing silicon carbide on a silicon substrate, a crystal lattice formed at the interface between the silicon carbide and the silicon substrate. There is a problem that the crystallinity of the formed silicon carbide and the morphology of the crystal surface are deteriorated due to the mismatch of the above. Therefore, when depositing silicon carbide on a silicon substrate, it is necessary to carbonize the surface of the silicon substrate in advance in a hydrocarbon atmosphere to form an extremely thin silicon carbide layer of about 100 Å [Ono et al., Electronic communication Society Technical Report, SSD80, (1980) 125].

However, in the process of carbonizing the surface of the silicon substrate, a porous defect is formed in the ultrathin surface silicon carbide layer, and silicon atoms diffuse from the silicon substrate toward the surface of the silicon carbide layer through the defect. (E.g. C.
J.Mogab et. Al., J. App. Phys. 45, (1974) 1
075]. This diffused silicon atom locally aggregates on the surface of the silicon carbide layer to form a silicon region. This silicon region causes the crystallinity and morphology of the ultrathin silicon carbide surface to deteriorate. When a silicon carbide film is formed on the ultrathin silicon carbide layer whose crystallinity and morphology are deteriorated by vapor phase epitaxy, the state of the surface of the ultrathin silicon carbide layer is inherited and the grown silicon carbide film. Defects occur in the film and the crystallinity of the film deteriorates, and the morphology of the surface deteriorates. Therefore, it is difficult to form a silicon carbide film having excellent crystallinity and surface morphology on the silicon substrate, in which electrical characteristics such as mobility and carrier density are easily controlled.

When a silicon carbide film is formed on a substrate having a coefficient of thermal expansion different from that of silicon carbide, when the substrate with silicon carbide having silicon carbide deposited at a high temperature is cooled to room temperature,
Due to the difference in thermal expansion coefficient, internal stress is generated in the formed silicon carbide film. This internal stress causes defects and cracks in the silicon carbide film. In addition, regardless of the type of substrate, a crystal lattice defect may occur in the silicon carbide film during film formation depending on the film forming conditions, the atmosphere in the film forming furnace, and the like. That is, it has been difficult to form a silicon carbide film having excellent crystallinity and surface morphology and excellent electrical characteristics by the conventional method for forming a silicon carbide film.

Therefore, the present invention provides a silicon carbide film excellent in crystallinity and surface morphology, which has substantially no defects in the film and facilitates control of electrical characteristics, and a substrate having such a silicon carbide film. And to provide a method for producing them.

When the substrate is made of silicon, the inventors of the present invention cause defects in the silicon carbide film and deteriorate the surface morphology.
Porous defects are formed in the surface silicon carbide layer, and silicon atoms enter the surface of the surface silicon carbide layer from the silicon substrate. In the case of a substrate other than silicon, silicon carbide and a silicon substrate are formed during film formation. Attention was paid to the fact that an internal stress is generated due to the difference in the coefficient of thermal expansion between and, and a crack is generated in the silicon carbide film due to this internal stress. Then, the above-mentioned porous defect generated during the formation of the silicon carbide film is absorbed by a defect which is a gettering source such as a groove which is partially introduced in advance on the surface of the substrate, and the defect is It has been found that the porous defects are reduced in the region of the silicon carbide film formed on the substrate surface in the region not introduced. Further, it was also found that the above-mentioned defects that become the gettering source introduced in advance can reduce cracks generated in the silicon carbide film. In addition, crystal lattice defects generated in the silicon carbide film depending on the film forming conditions and the state in the reaction furnace are also absorbed by the defects that are partially introduced into the surface of the substrate and serve as the gettering source. It has also been found that a silicon carbide film having a small amount of crystal lattice defects and excellent crystallinity can be formed in a region of the silicon carbide film formed on the substrate surface in a region where no defects are introduced.

[0010]

SUMMARY OF THE INVENTION The present invention relates to a silicon carbide film having a surface roughness having a center line average roughness (Ra) of 10 nm or less. The present invention also relates to a silicon carbide film having a surface hillock density of 200 / cm ² or less. Further, the present invention is a substrate having a silicon carbide film, wherein the silicon carbide film has a surface roughness such that a center line average roughness (Ra) of the surface is 10 nm or less, or a surface hillock density is 200 pieces. / Cm ²
The present invention relates to a substrate with a silicon carbide film, which is the following silicon carbide film. In addition, the present invention relates to a method for manufacturing a silicon carbide film, which comprises depositing a silicon carbide film on a substrate having defects.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below. Method of Forming Silicon Carbide Film The manufacturing method of the present invention is characterized in that a silicon carbide film is deposited on a substrate having a defect. Here, the defects of the substrate include, for example, geometrical defects and crystal lattice defects, which have the ability to absorb the defects generated in the silicon carbide film when the silicon carbide film is deposited (gettering). Source). Examples of the shape defects include grooves, spots, mechanical damage (surface irregularities), and the like. The crystal lattice defect includes, for example, a stacking fault which is one of surface defects. In a crystal having a close-packed structure, there are several types of arrangement in the plane overlapping manner with respect to the stacking axis. This is repeated in order to form a spatial grid, but this order may be disturbed. Such surface defects are stacking faults. In addition, the crystal lattice defects include dislocations and vacancies, and these defects are formed, for example, by controlling the manufacturing conditions of the substrate or by introducing an element different from the element forming the substrate. can do.

These defects serving as gettering sources may be partially provided on the surface of the substrate on which the silicon carbide film is deposited, or may be provided on part or all of the surface of the substrate facing the surface on which the silicon carbide film is deposited. You can When the defect is provided on the surface of the substrate on which the silicon carbide film is to be deposited, a silicon carbide film reflecting the defect is formed in the vicinity of the substrate where the defect exists, but when the defect is far from the substrate, the silicon carbide film has less defects. Therefore, the position where the defect is provided (the interval between the defect and the defect) can be appropriately adjusted according to the required size of the silicon carbide film. For example, as shown in FIG. 1, the grooves 2 which are one of the shape defects can be provided in a grid pattern on the surface of the substrate 1 on which the silicon carbide film is deposited. Then, in consideration of the size of the product using the silicon carbide film, lattice-like defects are formed so that a region having a size equal to or larger than the size of the product and having few defects can be obtained. Further, the grooves may be provided in a parallel line shape or the like other than the lattice shape.
Further, as shown in FIG. 2, spots 8 which are one of geometrical defects can be provided at regular intervals on the surface of the substrate 2 on which the silicon carbide film is deposited. Further, stacking faults and crystal lattice defects can also be provided as lattices, parallel lines, or spots.

On the surface of the substrate facing the surface on which the silicon carbide film is deposited, lattice-like or parallel-line-like defects as well as geometrical defects as spots, stacking faults and crystal lattice defects can be provided. . Further, it is possible to form defects on the entire surface by roughening the entire surface of the substrate, which is opposite to the surface on which the silicon carbide film is deposited, by sandblasting or the like.

Defects which are the gettering sources as described above can be introduced, for example, by reactive ion etching, ion milling, ion implantation, chemical etching, sand blasting, cutting method or polishing depending on the kind. . By the sandblasting method, the cutting method, the polishing, etc., lattice defects may be formed together with the geometrical defects. Among the defects, the grooves and spots can be produced by using, for example, a lithography process. When a lithography process is used, it can be incorporated as one step in a conventional semiconductor manufacturing process, and it is easy to put it into practical use. Further, the grooves and spots can be formed by physical etching typified by ion etching, chemical etching by a chemical reaction with acid or alkali, or mechanical cutting method. Mechanical damage such as surface irregularities can be introduced by a sandblast method or can be produced by polishing.

The substrate used in the manufacturing method of the present invention can be used without limitation as long as it can introduce the above defects and does not undergo thermal modification under the deposition conditions of the silicon carbide film. Examples thereof include silicon, sapphire, silicon carbide, magnesium oxide, aluminum nitride, titanium nitride, titanium carbide and diamond.
In the manufacturing method of the present invention, the deposition of the silicon carbide film is a well-known sublimation method [eg, Japanese Patent Publication No. 7-882.
74, Japanese Patent Publication No. 7-91153], liquid phase growth method [see, for example, JP-A-7-172998].
And vapor phase growth methods [eg, JA Powell et al., Journal of Electrochemical Society (J, Elec
trochem. Soc.) 134, (1987) 1558, and JP-A No. 7-118854). However, the vapor phase growth method is suitable from the viewpoint of obtaining a silicon carbide film having a large area and high crystallinity.

The silicon carbide film can be manufactured by the vapor phase growth method by placing the substrate in a reaction furnace and supplying a source gas to epitaxially grow silicon carbide on the surface of the substrate. As a raw material of silicon carbide, a silane compound and a hydrocarbon may be used, or an organic silicon compound may be used. As the silane-based compound that is the raw material gas, for example, dichlorosilane (SiH ₂ Cl ₂ ), SiH ₄ , SiCl ₄ , SiHCl ₃ or the like can be used. Examples of the hydrocarbon that is the raw material gas include:
Acetylene (C ₂ H _2), such as _{CH 4, C 2 H 6,} C 3 H 8 can be used. It is also possible to form a film only with a gas obtained by vaporizing an organic silicon compound such as (CH ₃ ) ₃ SiCl or (CH ₃ ) ₄ Si without using a silane compound and a hydrocarbon together. When a silicon substrate is used as the base, the surface silicon carbide layer can be formed in advance by heat treatment in a hydrocarbon atmosphere. Further, as described in JP-A-7-118854, at least a silane compound and a hydrocarbon may be alternately supplied into a reaction furnace under reduced pressure to epitaxially grow a single crystal silicon carbide film on a substrate. . A single-crystal silicon carbide film formed by epitaxial growth by forming a surface silicon carbide layer in advance and alternately supplying a silane compound and hydrocarbon into the reaction furnace under reduced pressure has particularly good crystallinity and surface morphology. Very good and preferable.

As described above, according to the method of the present invention, a defect which becomes a gettering source such as a groove or a spot is formed on a part (or the whole surface) of the substrate in advance, and the silicon carbide thin film is laminated on the substrate. It was done. If a substrate with defects that act as gettering sources is used, porous defects are gettered and reduced during the surface carbonization process or the silicon carbide film formation process to relax the stress in the film and generate cracks. Can be prevented or a crystal lattice defect generated during film formation can be absorbed to reduce the crystal lattice defect. Also, not only when using a silicon substrate as a base,
Even if a substrate other than silicon is used, if a substrate having a defect that serves as a gettering source is used, the stress in the film caused by the difference in the coefficient of thermal expansion between silicon carbide and the substrate can be relaxed and cracking can be prevented. It is possible to absorb the crystal lattice defects generated during the film formation and reduce the crystal lattice defects. As a result, a silicon carbide film having excellent electrical characteristics, crystallinity and surface morphology can be produced.

Silicon Carbide Film The silicon carbide film of the present invention obtained by the above-mentioned production method of the present invention has excellent surface morphology and has a center line average roughness (Ra) of 10 nm or less, preferably 0. .5-3n
It has a surface roughness in the range of m. The center line average roughness (Ra) of the surface is specified in JIS B 0601. In addition, the silicon carbide film of the present invention excellent in surface morphology has a hillock density of 200 /
It has a surface roughness of not more than cm ² , preferably in the range of 0 to 100 pieces / cm ² . The hillock density on the surface is determined by scanning microscope (SEM) or scanning tunnel microscope (ST
M), an atomic force microscope (AFM), or other scanning probe microscope.

The silicon carbide film of the present invention comprises α or β-Si.
It is a single crystal or polycrystalline film of C and has the above-mentioned surface characteristics. The α or β-SiC single crystal or polycrystalline film can be appropriately manufactured by controlling the manufacturing conditions. For example, when the CVD method is used, the temperature is, for example, about 1500 to 1600 ° C.
Α-SiC can be obtained by setting the range to 10
Β-SiC can be obtained by setting the temperature to around 00 ° C. Further, the single crystal and the polycrystal, the flow rate of the source gas,
It can be appropriately made by controlling the pressure and temperature. For example, a single crystal film can be formed by alternately introducing a source gas by a CVD method and controlling the flow rate, pressure, temperature, etc. of the source gas.
Further, the silicon carbide film of the present invention has, for example, 10 ¹⁷ to 10 ¹⁹ cm
Carrier density in the range of ² and 50 to 300 cm ² / (V · sec)
It has a mobility in the range of, and the electrical characteristics can be easily controlled. Furthermore, the film thickness can be appropriately selected depending on the application and the like. Generally, for example, the range of 5 to 10 μm is suitable for electronic devices such as high power semiconductor devices and communication high frequency devices, and the range of 2 to 5 μm is suitable for various sensors such as pressure sensors.

Substrate with Silicon Carbide Film The substrate with a silicon carbide film of the present invention is a substrate having the silicon carbide film of the present invention. That is, the center line average roughness (R
a) is a substrate having a silicon carbide film excellent in surface morphology having a surface roughness of 10 nm or less, preferably 0.5 to 5 nm. Alternatively, the surface hillock density is 200 pieces / cm ² or less, preferably 0 to 100 pieces / cm
It is a substrate having a silicon carbide film having a surface roughness in the range of ² and excellent in surface morphology. Examples of the substrate of the substrate with a silicon carbide film of the present invention include a silicon substrate, sapphire, silicon carbide, magnesium oxide, aluminum nitride, titanium nitride, titanium carbide and diamond. Further, a part of the substrate may be missing. The lack of a portion of the substrate can be formed, for example, by etching.

The silicon carbide film or the substrate with a silicon carbide film of the present invention can be manufactured from the silicon carbide film formed on the substrate by the manufacturing method of the present invention. For example, as the silicon carbide film, a substrate provided on the surface on which the silicon carbide film is to be deposited with defects serving as gettering sources at an interval capable of forming a silicon carbide film of a desired size is used, and a defect-free region on the substrate surface is used. It can be obtained by cutting out the deposited silicon carbide film by etching or the like. When a substrate having a defect on the surface opposite to the surface on which the silicon carbide film is deposited is used, it is possible to obtain a silicon carbide film having a relatively large area and excellent surface morphology. In addition, the substrate with a silicon carbide film uses a material to be a substrate of the substrate with a silicon carbide film as a substrate used in the method for producing a silicon carbide film, and a silicon carbide film is formed thereon by the production method of the present invention. Then, it is obtained by processing such as cutting so as to have a predetermined size and shape. that time,
A part of the substrate can be made to have a desired shape by etching or the like depending on the use of the element or the like.

The method for producing a silicon carbide thin film of the present invention will be described in detail below based on examples. Example 1 FIG. 3 is a vertical cross-sectional view showing, in the order of steps, the film forming method of the present invention performed in Example 1. In step (a), a single crystal silicon substrate 1 having a diameter of 3 inches was prepared. Next, in step (b), lattice-shaped grooves 2 were formed on the surface of the single crystal silicon substrate 1 by reactive ion etching. FIG.
Lattice-shaped grooves 2 formed by reactive ion etching
FIG. 3 is a plan view of a single crystal silicon substrate 1 having The reactive etching was performed under the conditions of CF ₄ 40 sccm, O _{2 10} sccm, RF power 300 W, and pressure 5 Pa. The grid is 1 cm
The grooves were set to have a width of 500 μm and a depth of 0.5 μm.
The groove can also be formed by ion milling.
In step (c), a silicon substrate is placed in a reaction furnace and heated to 1020 ° C. in an acetylene gas 4 and hydrogen atmosphere,
The surface carbonized layer 3 was previously formed on the silicon substrate 1 by keeping it for another 60 minutes. The conditions of surface carbonization at this time are shown in Table 1.
Shown in The film thickness on the surface of the silicon substrate was measured by ellipsometry and found to be 80Å.

[0023]

[Table 1]

After the carbonized layer 3 is formed in the step (d), the silicon carbide film 6 is formed by continuously supplying the silane compound and the hydrocarbon into the reaction furnace at the substrate temperature of 1020 ° C. The membrane was carried out. As a cytin compound, dichlorosilane (SiH ₂ Cl ₂ ) 5 is used as a hydrocarbon and acetylene (C
₂ H ₂ ) 4 was used. It is also possible to lower the temperature in the furnace, take out the silicon substrate which has been subjected to surface carbonization once, place it in a separate reaction furnace, and raise the temperature to 1020 ° C. before forming a film. Details of the growth conditions for the silicon carbide film are shown in Table 2.

[0025]

[Table 2]

FIG. 4 is a scanning electron microscope (SEM) image of the surface of the surface silicon carbide layer 6 formed by carbonizing the silicon substrate surface in the step (c). The observation was performed in a region 7 surrounded by the groove 2 as a gettering source. From this SEM image, it can be seen that the surface of the silicon carbide layer in region 7 has few defects and is smooth. FIG. 5 is a scanning electron microscope (SEM) image of the surface of the silicon carbide film formed in step (d). The observation was performed in a region 7 surrounded by the groove 2 as a gettering source. From this SEM image, it can be seen that the surface of the silicon carbide film in region 7 is smooth. FIG. 6 is a scanning tunneling microscope (STM) image of the surface of the silicon carbide film formed in step (d). JIS B 0601 of the area 7 on the surface of the silicon carbide film
The centerline average roughness (Ra) was 1.6 nm. The hillocks in the region 7 on the surface of the silicon carbide film have a density of 10 pieces / cm.
^{Was 2} . X-ray diffraction measurement was performed to examine the crystallinity of the silicon carbide film. The only observed peak was due to the cubic silicon carbide (n00) plane. The full width at half maximum of the 200-plane peak of this cubic silicon carbide was 0.204 degrees. When the electrical characteristics of the obtained silicon carbide film were measured by the Hall measurement method, the carrier density of the silicon carbide film was 1.7 ×
It was 10 ¹⁷ cm ⁻³ and the mobility was 220 cm ² / V · sec. The results are summarized in Tables 3-5.

Comparative Example A silicon carbide film was formed on a single crystal silicon substrate which did not have defects as a gettering source. FIG.
It is a longitudinal cross-sectional view which shows the film-forming method of a comparative example in process order. In step (a), the silicon substrate 11 is prepared, and in step (b),
The surface of silicon substrate 11 was carbonized to form silicon carbide layer 12. There are concave defects 13 in the silicon carbide layer 12. In the step (c), the silicon carbide film 16 is formed on the silicon carbide layer 12.
Was formed. Island-shaped protrusions (hillocks) 14 are present on the silicon carbide film 16. The details of the film forming conditions are the same as in Table 2. FIG. 8 is a scanning electron microscope (SEM) image of the surface of the silicon carbide layer 12 formed in the step (b). From this SEM image, it can be seen that many concave defects shown by 13 in FIG. 7 are present on the surface. The density of this concave defect is 3 ×
It was 10 ³ pieces / cm ² . FIG. 9 shows a scanning electron microscope (SEM) of the surface of the silicon carbide film 16 formed in the step (c).
It is a statue. From FIG. 9, it was confirmed that a large number of island-shaped protrusions (hillocks) were clearly present on the surface of the silicon carbide film formed by this method. FIG. 10 shows a scanning tunneling microscope (ST) of the surface of the silicon carbide film 16 formed in the step (c).
M) Image. From the STM image, it was found that a large number of island-shaped hillocks, which were induced by defects in the silicon carbide layer formed by carbonization, were present on the surface of the silicon carbide film. Hillock
The height was about 100 nm and the density was 300 pieces / cm ² . The center line average roughness (Ra) of the surface was 12.0 nm. X-ray diffraction measurement was performed to examine the crystallinity of the silicon carbide film. The only observed peak was due to the cubic silicon carbide (n00) plane. The full width at half maximum of the cubic silicon carbide 200 plane peak of the silicon carbide film obtained from the X-ray diffraction measurement is 0.
It was 327 degrees. The mobility of the silicon carbide film is 10 cm.
^{At 2} / V · sec, the carrier density was 1.2 × 10 ¹⁹ cm ⁻³ .

Example 2 Instead of the grid-like grooves, circular spots 8 as shown in FIG.
Single crystal silicon substrate 1 having a diameter of 3 inches
A silicon carbide film was formed by the process shown in FIG. 3 in the same manner as in Example 1 except that was used. The circular spots 8 were provided by reactive ion etching at positions corresponding to the intersections of the lattice of FIG. 1 (at intervals of 1 cm in length and width). Reactive etching is CF ₄ 40sccm, O ₂ 10sccm, RF power 300
It was carried out under the conditions of W and pressure of 5 Pa. The spot is 1m in diameter
m, depth 0.5 μm. A silicon carbide single crystal film is grown on the silicon substrate provided with the spots in the same manner as in Example 1, and the surface of the silicon carbide film is SEM, ST.
As a result of M observation, it was found that the hillock density was 50 pieces / cm ² in the region between the spots, and the hillock was reduced as compared with the surface of the silicon carbide film produced by the conventional method. The center line average roughness (Ra) of the surface was 2.3 nm. From the result of measuring the electric characteristics of the silicon carbide film, the mobility is 100.
It was found that both of the carrier density of 7.5 × 10 ¹⁷ cm ^{-3 in} cm ² / V · sec and the carrier density are superior to those of the silicon carbide film forming method described in the comparative example.

Example 3 A silicon carbide single crystal film was formed in the same manner as in Example 1 except that the grid-shaped grooves 2 had a width of 500 μm and a depth of 2 μm and were formed by chemical etching. The etching solution used for the chemical etching is a mixed solution of HNO ₃ : HF = 1: 8. When the surface of the obtained silicon carbide film was observed by SEM and STM, the hillock density was 10 pieces / cm ² in the region between the lattices formed by etching, which was higher than that of the silicon carbide film surface produced by the conventional method. It was found that hillocks were reduced. Center line average roughness (R
a) was 2.0 nm. As a result of measuring the electrical characteristics of the silicon carbide film, the mobility was 113 cm ² / V · sec, the carrier density was 6.7 × 10 ¹⁷ cm ^−3, and both the carrier density was the silicon carbide film described in the comparative example. It was found to be superior to the film forming method.

Example 4 A silicon carbide single crystal film was grown in the same manner as in Example 2 except that the spot 8 had a diameter of 1 mm, a depth of 2 μm, a spot interval of 100 μm, and was formed by chemical etching. . The chemical etching was performed under the same conditions as in Example 3. When the surface of the silicon carbide film is observed by SEM and STM, the hillock density is 60 / cm ² in the region between the sbots formed by etching, and the hillock is reduced as compared with the silicon carbide film surface produced by the conventional method. I found out that The center line average roughness (Ra) of the surface obtained by STM measurement was 2.6 nm. From the results of measuring the electrical characteristics of the silicon carbide film, the mobility is 95 cm ² / V · sec.
It was found that the carrier density was 8.0 × 10 ¹⁷ cm ⁻³ and both carrier densities were superior to the silicon carbide film forming method described in the comparative example.

Embodiment 5 FIG. 11 is a vertical cross-sectional view in the order of steps of the film forming method in this embodiment. In step (a), a single crystal silicon substrate 21 having a diameter of 3 inches was prepared. Then in step (b),
Mechanical damage (surface irregularities) 22 was provided by a sandblast method on the entire surface of one surface (the surface opposite to the surface on which silicon carbide was formed) of this single crystal silicon substrate 21. The mechanical damage may be introduced by cutting mechanically or by polishing. In the step (c), the carbonized surface layer 23 was formed on the surface side of the silicon substrate 21 not having the mechanical damage 22 in the same manner as in Example 1. Then, in step (d), a silicon carbide single crystal film 24 was grown on surface carbonized layer 23 in the same manner as in Example 1. When the surface of the silicon carbide film was observed by SEM and STM, hillocks could not be confirmed within the measurement range. This means that hillocks are reduced as compared with the surface of the silicon carbide film produced by the conventional method. As a result of measuring the electrical characteristics of the silicon carbide film, the mobility was 80 cm ² / V · sec, the carrier density was 1.1 × 10 ¹⁸ cm ^−3, and both the carrier density was the silicon carbide film described in the comparative example. It was found to be superior to the film forming method. It should be noted that substantially the same result can be obtained even if the mechanical damage is locally provided not on the entire back surface but on the back surface. Similar results can be obtained by locally introducing mechanical damage to the substrate surface.

Example 6 As shown in FIG. 12, a lattice defect (gettering source) 32 was formed in a lattice shape by ion implantation instead of the lattice-shaped groove 2 shown in FIGS. A silicon carbide single crystal film was formed in the same manner as in Example 1. That is, step (a)
Then, a single crystal silicon substrate 31 having a diameter of 3 inches
Was prepared. Next, in step (b), lattice-shaped lattice defects 32 are formed on the surface of the single crystal silicon substrate 31 by ion implantation.
Was provided. Ion implantation was performed by a method of implanting ions using a photoresist pattern having openings formed in a lattice pattern as a mask. FIG. 13 shows a vertical cross-sectional view of the photoresist 33 and the lattice-shaped openings 34 provided on the surface of the silicon substrate 31. The spacing between the grid-shaped openings 34 was 1 cm, and the width of the openings 34 was 500 μm. Implanted ions are aluminum ions (Al ⁺ ). An ion implanter was used for ion implantation. As the implantation conditions, the ion accelerating voltage is 200 keV and the aluminum ion implantation amount is 1 ×.
It was 10 ¹⁵ cm ^-2 . After implanting ions, the photoresist 33 was removed to obtain a silicon substrate 31 provided with lattice defects 32.

In step (c), the silicon substrate was placed in the reaction furnace, and acetylene gas 4 was used to form the carbonized surface layer 35 on the silicon substrate 31 in the same manner as in Example 1. Further, in step (d), a silane compound (dichlorosilane (SiH ₂ Cl ₂ ) 5) and a hydrocarbon (acetylene (C ₂ H ₂ ) 4) are alternately supplied into the reaction furnace under the same conditions as in Example 1. By doing so, the silicon carbide film 36 was formed. SE on the surface of the silicon carbide film
Observation by M and STM shows that the hillock density is 10 / cm ² in the region surrounded by the ion-implanted lattice, and that the hillock is reduced compared to the silicon carbide film surface produced by the conventional method. I understood. The center line average roughness (Ra) of the silicon carbide film surface was 1.9 nm. From the result of measuring the electrical characteristics of the silicon carbide film, the mobility is 150c.
m ² / V · sec, carrier density is 6.0 × 10 ¹⁷ c
It was found that both m ^-3 and carrier density were superior to the silicon carbide film forming method described in the comparative example.

[0034]

[Table 3]

[0035]

[Table 4]

[0036]

[Table 5]

Table 3 shows the electrical characteristics of the silicon carbide film.
Table 4 shows the full width at half maximum of the 200-plane peak of cubic silicon carbide, which is a measure of the crystallinity of the silicon carbide film, and Table 5 shows the surface morphology of the silicon carbide film. From Tables 3, 4, and 5, it can be seen that the silicon carbide film formed according to the present invention is extremely excellent in crystallinity, surface morphology and electrical characteristics.

As described above, it has been confirmed that the surface of the surface silicon carbide layer formed on the surface of the silicon substrate to which the defect to be the gettering source has been imparted has the defect reduced and the surface morphology is improved. Then, subsequently, when a silicon carbide film is formed on the surface silicon carbide layer in which the defects are reduced and the surface morphology is improved, the formed silicon carbide film is a silicon that does not give a defect as a gettering source. It was confirmed that the crystallinity and surface morphology were improved as compared with the silicon carbide film on the substrate. As described above, according to the present invention, it is possible to form a silicon carbide single crystal film having excellent crystallinity and surface morphology, and as a result, excellent electric characteristics.

[Brief description of drawings]

FIG. 1 is a single crystal silicon substrate 1 having lattice-shaped grooves 2.
FIG.

FIG. 2 is a plan view of a single crystal silicon substrate 1 having spots 8.

FIG. 3 is a vertical cross-sectional view showing the film forming method of Example 1 in the order of steps.

FIG. 4 is a scanning electron microscope (SEM) image photograph in place of a drawing showing a surface state of a surface silicon carbide layer formed in step (c) of Example 1.

FIG. 5 is a scanning electron microscope (SE) instead of a drawing showing the surface state of the silicon carbide film formed in the step (d) of Example 1.
M) Image photograph.

FIG. 6 is a scanning tunneling microscope (STM) showing the surface state of the silicon carbide film formed in the step (d) of Example 1.
image.

FIG. 7 is a vertical cross-sectional view showing a film forming method of a comparative example in the order of steps.

FIG. 8 is a scanning electron microscope (SEM) image photograph in place of a drawing, which shows a surface state of the surface of the silicon carbide layer formed in the step (b) of the comparative example.

FIG. 9 is a scanning electron microscope (SE) instead of a drawing showing the state of the surface of the silicon carbide film formed in the step (c) of the comparative example.
M) Image photograph.

FIG. 10 is a scanning tunneling microscope (STM) image showing the state of the surface of the silicon carbide film formed in step (c) of the comparative example.

FIG. 11 is a vertical cross-sectional view in the process order of the film forming method according to the fifth embodiment.

FIG. 12 is a vertical cross-sectional view in the order of steps of a film forming method of Example 6.

FIG. 13 is a vertical cross-sectional view of the photoresist and the grid-shaped openings formed in the step (b) of Example 6.

Claims (13)

[Claims] 1. A silicon carbide film having a surface roughness having a center line average roughness (Ra) of 10 nm or less. 2. The center line average roughness (Ra) of the surface is 0.5 to 3.
The silicon carbide film according to claim 1, having a thickness in the range of nm. Hillock density of 3. A surface 200 / cm ²
The following is a silicon carbide film. 4. The surface hillock density is 0 to 100 pieces / c.
The silicon carbide film according to claim 3, wherein the silicon carbide film has a range of m ² . 5. A substrate having a silicon carbide film, wherein the silicon carbide film is the silicon carbide film according to any one of claims 1 to 4. 6. The substrate with a silicon carbide film according to claim 5, wherein a part of the substrate is absent. 7. The substrate with a silicon carbide film according to claim 6, wherein a part of the substrate is formed by etching. 8. A method of manufacturing a silicon carbide film, which comprises depositing a silicon carbide film on a substrate having defects. 9. The method according to claim 8, wherein the surface of the substrate on which the silicon carbide film is deposited has a partial defect. 10. The manufacturing method according to claim 8, wherein a part or all of the surface of the substrate facing the surface on which the silicon carbide film is deposited has a defect. 11. The manufacturing method according to claim 8, wherein the defect is a geometrical defect or a crystal lattice defect. 12. The defect is introduced by reactive ion etching, ion milling, ion implantation, chemical etching or sandblasting.
The production method according to the paragraph. 13. The manufacturing method according to claim 8, wherein silicon carbide is deposited on the surface of the substrate by alternately supplying the silane compound and the hydrocarbon onto the substrate.